I think alot of people find the Cabas Piano to be small. But I found the size to be perfect for me. The Speedy 30 is HUGE! I find it to be very bulky.
The thing with the Cabas Piano is the fact that it's a shoulder bag (hands free), but the LV leather on the bottom is gonna be a big pain. Especially when setting it down, you have to inspect the area prior to placing it down. Or you can really just not care. LOL But another + for the Cabas is that it's bottom base won't sag too much with a heavy load.
The Speedy 30 is a classic. A LV collector definitely has one in their collection. I use my Speedy 30 as a short distance travel bag. The thing that upsets ppl with it is the fact that it sags after awhile. Some people fix it by placing papers/cards inside the bag. But I just stop caring, it sags so let it sag. LOL
I have both bags. Facing off the Cabas VS Speedy...hmm...It's like a classic (Speedy 30) versus slightly classic too w/ a heavier price tag but with shoulder straps (so it's very practical for everyday use). How will you use your bag?
Both are LV so whatever you get it's gonna be a great one. LOL Why not try a Batignolles? Horizontal / Vertical whatever you like. hehe